Bolted Connections in Cold-Formed Steel: Reliability Analysis for Rupture in Net Section

Abstract

This article presents 93 unpublished experimental results for rupture in the net section of bolted connections in cold-formed steel angles and channels. The article includes a study of the strength reduction coefficient in order to account for the shear lag effect. Predictions of connection strength by Brazilian and American design codes are considered. By comparing experimental results with design code predictions, model error (professional factor) statistics are evaluated. Model errors are incorporated in reliability analyses of typical connections to investigate their effects on connection safety. It is shown in the article that model errors have a significant impact on connection safety. Consideration of model errors leads to significant reductions in reliability indices, which are found to be less than the recommended target reliability levels. The model error statistics obtained herein are used to find the resistance factors that would be required to achieve the target reliability index in the design of bolted connections for net-section rupture. These factors are smaller than the current ϕ=0.65 used in the American Iron and Steel Institute code. Other suggestions for improvement of the North American code are also presented.